Apparatus for the directional transmission and reception of wave energy



H. HECHT Aug. 7, 1934.

APPARATUS FOR THE DIRECTIONAL TRANSMISSION AND RECEPTION OF WAVE ENERGY Filed April 24, 1930 to By Patented Aug. 7, 1934 PATENT OFFICE,

APPARATUS FOR THE DIRECTIONAL TRANS- MISSION AND ENERGY Heinrich Hecht, Kiel,

RECEPTION F WAVE Germany, assignor to Electroacustic Gesellschaft mit beschrankter Haftung, Kiel, Germany, a firm Application April 24, 1930, Serial No. 446,873 In Germany April 30, 1929 1 Claim.

The present invention relates to apparatus for the directional transmission and reception of wave energy, and particularly to modifications of, or improvements in arrangements in which emis- 5 sion of the directional energy beam or the determination of its direction in case of receiving, is carried out with a plurality. of fixed oscillators distributed in two or three dimensions in connection with a variable compensator. Amongst the possible arrangements of this kind the completely symmetrical arrangements take precedence, since, with them the directional sharpness of transmission or reception is uniform in all directions. An arrangement of this kind is for instance described in the U. S. patent granted to Hecht and Stenzel No. 1,893,741, dated January 10, 1933.

In many cases, however, it is preferable to forego this advantage, especially when the space which is available for the installation is not of the same dimensions in all directions. This is for instance the case when such a device is installed at the bottom of a relatively small vessel near the bow, which is the best location, being furthest removed from engine and propeller noises. The beam of the vessel at that point is notv very large, so that with a completely symmetrical, i. e. circular arrangement of oscillators, the diameter of the circle would have to be very small and thus the directional effect would be very broad. On the other hand in the direction of the keel, a very large space is available, which would permit the spacing at a considerably larger radius, and thus considerably sharpen the directional character of the system. For the purpose of meeting the difliculties of properly compensating all oscillators, which are arranged in an only partly symmetrical configuration inorder to accommodate them in places just described, the present arrangement has been devised as an improvement on and a further specific development of the subject matter of my aforesaid earlier application.

By the term oscillator as used in the present description and claim is understood a device-of well known type in this art, through which wave energy such as electric or sound radiation, can either be transmitted or received by local electric circuit arrangements.

compensator I understand, broadly speaking, a device for introducing suitable time retardation in the relative flowbf energy-for instance sound or electric wave energythrough several energy consumers or producers for the purpose of bringing about a desired phase relation between the individual energy effects produced in said consumers or producers by the energy flow. Devices of this character are today well known instrumentalities, in particular in the acoustic and electric signalling art. By employing such time retardation in the energy fiow, it is possible for instance in energy consumers or receivers, which for outside reasons do not happen to individually receive energy simultaneously, to bring about a simultaneous energy effect in all of them by retarding through compensators the flow in those which receive their energy too early. How such compensators, for instance in the form of electric filter circuits, may be particularly usefully employed in direc- 70 tional wave energy transmission or reception is also well known in the art.

It is further known in the prior art to use an arrangement for directional transmission or reception of wave energy with a plurality of oscillators, all of which are connected to the same indicator or to the same wave generator, this connection being alternative according to whether it is desired to receive or to transmit. Such a group of oscillators has a so-called characteristic, which manifests itself for instance in case of reception in the addition of the wave energy, arriving from a certain direction, in all oscillators, provided this wave energy reaches all oscillators simultaneously. If the energy arrives from certain other directions the total eiiect of all oscillators may be a partial or the entire neutralization, and thus nullification of the effect in the indicator, which is for instance the case when the arriving waves strike the several oscillators at such difierence in time that oppositely directed efiects are produced in some of the oscillators which result in a neutralization of the total effect in the telephone. This neutralization occurs for instance if in one oscillator a positively directed wave arrives so much later over the time at which that positive wave has arrived at a differently located oscillator, that in the last-mentioned oscillator the wave has swung in the meantime to the negative side with the result that both halves neutralize one another if the two rect connection between the oscillators and the telephone and without a compensator, according to which all those source of sound are observed with maximum intensity which are located on a line running through the center of the circle and extending on both'sides of the circular plane. As is well known such a line or circular arrangement of the oscillators is two-valued, because even if a maximum indication is observed, the observer cannot tell on which side of the oscillators the source of sound is located. L

It is, therefore, more advantageous to use a circularly arranged group so that the plane of the circle coincides with the plane in which the beam of wave energy extends. It is then obvious that for instance for sound waves which arrive in the plane in which the circle of oscillators extends, the circular arrangement will not have a characteristic such as was mentioned before, i. e. it will not have a natural characteristic, because from no direction within the plane of the circle all oscillators can be encountered simultaneously by the arriving sound waves in case of reception. Such a circular arrangement of oscillators so placed can be given, however, an artificial characteristic by connecting the oscillators not directly with the telephone, or in case of transmission with the wave energy transmitter, but by way of artificial retardation devices which are adjustable in suitable manner. It becomes obvious immediately that in such a case for each directional position of the distant source of sound within the plane of the circle one, and only one adjustment of this retardation device exists in which all time differences in the arrival of a certain wave at all oscillators are compensated by the retardation devices in such manner that the impulse effect exerted by the different oscillators upon the telephone becomes simultaneous, and thus a maximum sound effect is produced in the telephone. for all directions of the sound source within the plane of the circle, in other words the direction determination with circular arrangement of oscillators and in the last described manner and within the plane of the circle is single valued and of the same intensity in all of these directions.

The same is true.,when such an arrangement is used for transmission in which case the telephone is replacedby a wave energy generator such as an alternating current generator.

The maximum effect with such a circular arrangement is the sharper and at the same time the narrower, the larger the diameter of the circle. In this respect such an arrangement is similar to a straight line arrangement of the oscillators in which the maximum eflect is the sharper and narrower in the most favorable direction, the longer the line on which the group of oscillators is spaced, 1. e. thefurther the two outermost oscillators of the group are located apart.

According to the present invention, full advantage can be taken of an available unsymmetrical space by such as near the bow of a vessel, by arranging the oscillators symmetrically with reference to two or more main axes. The most important cases in single plane arrangements are the bi-axial symmetrical systems, to which the present constructional examples particularly refer. In that case the maximum eflect in the direction of the keel is not as sharp as might be de-' sired, but in the. direction of the vessel's beam, the maximum effect becomes exceedingly sharp.

This maximum is of the same value In the accompanying drawing.

Fig. 1 shows the simplest arrangement, namely four oscillators arranged at the comers of a rhombus.

Fig. 2 shows an arrangement of a larger numher of oscillators in two crossed straight-lines.

Fig. 3 shows an arrangement of receivers in the form of an ellipse.

Fig. 4 shows the example of Fig. 3 with the corresponding compensator.

, In the drawing, the oscillators are repre sented by small circles.

In all these arrangements, the directional sharpness grows on turning the energy beam out of the direction of the larger axis into that of the smaller axis, where it reaches its maximum, and beyond that decreases again.

While the compensator for the elliptical arrangement of the oscillators may be designed within the scope of the present invention in several different ways, the most practical and efficient design is in such a way that a telephone is connected to one end of a retardation line, and the receivers are moved along the line. In such an arrangement, it must be observed that, if relatively simple compensators are desired, only those receivers can be connected to the same line, which are positioned on a circle around the center of the ellipse. If, for instance, four receivers have the same distance from the centre, then the con- 'nections for all these four receivers can slide over the contacts of one and the same line.

Such an arrangement is shown in Fig. 4, in which the oscillators, which are arranged on the ellipse c, are indicated by l to 8. Of these 1 to 4 lie on a small circle with the. radius 11, and 5 to 8 on a larger circle with the radius re. The corresponding compensator lines are 101 and k: with the respective end resistances 'LDl and 1.02. Both lines are simultaneously connectible to the telephone h through the transformer t. Separate contact paths in and b: with separate sliding-contact carriers m1 m: are allotted to each of the two circular groups, each of the four appertaining oscillators of each group being connected at one terminal to a corresponding insulated sliding contact on the pertaining contact carrier. The other terminals of oscillators 1-4 are connected to the common collecting contact i1, and those of oscillators 5-8 are connected to the common collecting contact ii. These collecting contacts are in turn connected through the respective lines l1 lg to the bus-bars 81 s: 'of the two retardation lines In 162. The compensator is illustrated in that setting which, at the reception of impulses, corresponds to a wave front arriving in the direction of the double-feathered arrow, a setting in which the sharpest possible maximum would be attained. The compensator is a double-acting one, that is, the lines are 5 doubly utilized i. e. for two 180 ranges, for which reason each link of each compensator chain is connected with two corresponding contacts of the respective contact paths b1 and In.

For the transmission of waves, a generator, shown in dotted lines is used instead of the indicator (telephone) h. For the transmitted energy beam the corresponding effects are obtained, that is, the beam is sharpest at right angles to the larger axis of the ellipse, and is broadest at right angles to the smaller axis. Since, so far as the purpose of the present invention is concerned, it is immaterial whether a transmitter or a receiving indicator is used, I have used in the claim for the indicator h and the transmitting alternating current machine, shown in dotted lines, the generic expression electromechanical impulse translating means". The oscillators may be sound transmitters or receivers, or electrical wave transmitters or receivers. The style and the fineness of division of the compensator into its constituent sections conforms with the desired adjusting or directional sharpness, and with the division of the scale (linear or not linear, not shown in Fig. 4), over which the sliding contact carriers m1 and ma move.

I claim:

Arrangement for the directional transmission and reception of wave energy comprising in combination an electro-mechanical impulse translating means, a plurality of wave energy oscillators spaced in at least two dimensions; a compensating means having a plurality of retardation lines and a switching means adapted to connect all of said oscillators in diflerent compensator steps through said compensating means to said impulse translating means for compensating the diflerences in travelling time of the same impulse with respect to the difierent oscillators, due to the difierent relative positions of the oscillators to the wave front of the energy beam, the said oscillators being arranged in a figure symmetrical to two axes of difierent lengths, located substantialy in a plane in parallel to the plane of propagation of sound energy, said oscillators being subdivided into circular groups, each circular group being allotted to one individual retardation line of the compensator and means for adjusting all retardation lines simultaneously for combining the response of all oscillators of all groups into a simultaneous maximum wave energy eifect for a given wave beam direction.

HEINRICH HECHT. 

